Image sensors and optical devices

What mainly determines the emission color (wavelength) of an LED?

  1. AThe shape of the package
  2. BThe direction of the drive current
  3. CThe band gap of the semiconductor used in the light-emitting layer
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Answer: C. The band gap of the semiconductor used in the light-emitting layer

In an LED, light with energy corresponding to the band gap is emitted when electrons and holes recombine. The wavelength is λ(nm) ≈ 1240 / Eg(eV), so the larger the band gap, the shorter the wavelength (toward blue).

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  3. Why do fast-moving subjects appear distorted with the rolling shutter method of CMOS image sensors?
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